There are a number of processes for providing a surface layer of a fabric, such as leather or simulated leather, onto all or part of the surface of molded plastic parts. Using an injection molding process and pre-inserting a fabric surface piece in front of or into the mold is discussed in JP 54-018,039; JP 57-029,436; DE 4,015,071; EP 1,157,799; and U.S. Pat. No. 4,849,145.
In JP 54-018,039 a fabric is held in the mold and forced against the opposite side of the mold cavity by injected plastic. DE 4,015,071 and JP 57-029,436 teach the use of a film between the fabric and the injected, molten plastic. In EP 1,157,799 a fabric is laminated initially to a formable thermoplastic foil and then a preform is prepared by generally shaping the laminated material, for example by deep drawing, to correspond generally to the finished part design. Then the preform is inserted into the injection mold where the molten plastic is injected and the fabric/foil laminate preform forms all or part of the outer surface of the finished part. However, none of these mention any technique for securing and covering the fabric edges.
In U.S. Pat. No. 4,849,145 leather fabric surfaces are provided on molded plastic parts. In this reference the injected plastic that forms the part is intended to flow to the edges of the inserted fabric piece to abut and seal the peripheral edges of the leather fabric. It has been found, however, that this process results in poor part appearance because the fabric edge is not consistently covered by the injection molded plastic. The resulting fabric/plastic interface or edge that is visible on the part surface is at least partly open and/or irregular. Thus, any of these methods requires subsequent process steps to cut or trim the fabric and/or to cover the edges in some fashion to provide secure and aesthetically pleasing fabric edges. The attachment and use of a separate trim piece is not acceptable because it requires multiple pieces and assembly steps to obtain an acceptable appearance and these additional pieces require greater part thickness and space. This process also results in a trim piece that is more easily separated from the fabric surface. The problems with the fabric edges are especially pronounced in fabrics that are more easily compressed in the first injection step and expand significantly after the first molding cavity is removed.